Quick reference

OpenSCAD cheat sheet

Every OpenSCAD primitive, transformation, boolean operation, function, operator, and special variable on a single page. Bookmark it, search it (Ctrl/⌘ + F), and paste any snippet straight into the AI CAD Modeler to see it render live.

Based on OpenSCAD v2021.01 — the version bundled with the AI CAD Modeler.

Everything below works in the browser WebAssembly build. For deeper dives, jump to the per-topic reference pages linked from the docs hub.

Syntax

Variables, ternaries, functions, modules, includes

var = value;Assignment

var = cond ? a : b;Ternary

var = function (x) x + x;Function literal

module name(...) { ... }Define a module

function name(...) = ...;Define a function

include <file.scad>Inline a file

use <file.scad>Import modules/functions only

Constants

Built-in values

undefThe undefined value

PI≈ 3.14159265358979

true / falseBooleans

Operators

Arithmetic, comparison, logical

Operator	Meaning	Operator	Meaning
`n + m`	Addition	`n < m`	Less than
`n - m`	Subtraction	`n <= m`	Less or equal
`n * m`	Multiplication	`a == b`	Equal
`n / m`	Division	`a != b`	Not equal
`n % m`	Modulo	`n >= m`	Greater or equal
`n ^ m`	Exponentiation	`n > m`	Greater than
`a && b`	Logical AND	`a \|\| b`	Logical OR
`!a`	Logical NOT	`v[i]`	Vector index

Special variables

Dollar-prefixed runtime knobs

Variable	What it controls
`$fn`	Number of facets a circle/sphere is approximated by. Overrides `$fa` / `$fs`.
`$fa`	Minimum facet angle (default 12°). Bigger ⇒ coarser, faster.
`$fs`	Minimum facet size (default 2 mm). Smaller ⇒ smoother on small parts.
`$t`	Animation time, 0.0 → 1.0.
`$vpr` / `$vpt` / `$vpd` / `$vpf`	Viewport rotation / translation / camera distance / FOV.
`$children`	Number of children passed into the current module.
`$preview`	`true` during F5 preview, `false` during F6 render.

Modifier characters

Prefix any statement to debug

*Disable (skip this subtree)

!Show only this subtree

#Highlight (debug)

%Background (transparent / not in final mesh)

2D primitives

Shapes that live in the XY plane

Call	Description
`circle(r \| d=...)`	Circle. Use `$fn` to control facets.
`square(size, center=false)`	Square or rectangle. `size` = number or `[w,h]`.
`polygon(points, [paths])`	Arbitrary 2D polygon from a list of points.
`text(text, size, font, halign, valign, ...)`	Generate 2D text using an installed font.
`import("file.dxf\|svg", convexity)`	Import a 2D shape from DXF or SVG.
`projection(cut=false)`	Flatten a 3D shape to 2D (top-down silhouette).

3D primitives

Solid building blocks

Call	Description
`sphere(r \| d=...)`	Sphere centered on origin.
`cube(size, center=false)`	Box. `size` = number or `[w,d,h]`.
`cylinder(h, r \| d, center=false)`	Right circular cylinder.
`cylinder(h, r1, r2 \| d1, d2)`	Cone / truncated cone.
`polyhedron(points, faces, convexity)`	Arbitrary closed mesh from points + faces.
`import("file.stl\|off\|amf\|3mf")`	Import a mesh.
`linear_extrude(height, center, twist, slices, scale)`	Extrude a 2D shape straight up (with optional twist).
`rotate_extrude(angle, convexity)`	Sweep a 2D shape around the Z axis.
`surface(file="map.png\|dat", center, convexity)`	Build a heightmap from a PNG or DAT file.

Transformations

Move, rotate, scale, mirror, color

Call	Description
`translate([x, y, z])`	Move by a vector.
`rotate([x, y, z])`	Rotate around X, then Y, then Z (in degrees).
`rotate(a, [x, y, z])`	Rotate `a`° around an arbitrary axis.
`scale([x, y, z])`	Scale per axis. Use 1.0 to leave an axis alone.
`resize([x, y, z], auto, convexity)`	Resize to fit a target bounding box.
`mirror([x, y, z])`	Mirror across the plane normal to the vector.
`multmatrix(m)`	Apply an arbitrary 4×4 transform matrix.
`color("name" \| "#hex" \| [r,g,b,a])`	Color a subtree for preview.
`offset(r \| delta, chamfer)`	2D offset (round or chamfered).
`hull()`	Convex hull of all children.
`minkowski(convexity)`	Minkowski sum of children — great for fillets & rounding.

Boolean operations

Combine shapes

union() { ... }Merge children (default)

difference() { A; B; C; }A minus B minus C

intersection() { ... }Keep only shared volume

Lists & vectors

Indexing, slicing, dot-notation

list = [a, b, c];Create a list

v = list[2];Index (0-based)

v = list.z;Dot notation (x / y / z)

len(list)Length

concat(a, b)Concatenate

[for (i = range) expr]List comprehension

List comprehensions

Build lists declaratively

[for (i = range_or_list) expr]Generate

[for (i = ...) if (cond) expr]Filter

[for (i = ...) if (c) a else b]Branch

[for (i = ...) let (j = ...) expr]With let

[each list]Flatten

[for (i = 0; i < n; i = i+1) i]C-style for

Flow control

for, if, let, intersection_for

for (i = [start : end]) { ... }Range

for (i = [start : step : end]) { ... }Range with step

for (i = [a, b, c]) { ... }List

for (i = ..., j = ...) { ... }Nested

intersection_for(i = ...) { ... }Intersect iterations

if (cond) { ... } else { ... }Conditional

let (x = expr) { ... }Local binding

Type tests

Predicates for runtime types

is_undef(x)True iff x is undef

is_bool(x)True iff boolean

is_num(x)True iff number

is_string(x)True iff string

is_list(x)True iff list/vector

is_function(x)True iff function literal

Other built-ins

Strings, search, version, debug

echo(...)Print to console

assert(cond, msg)Halt on failure

render(convexity)Force CGAL render of subtree

children([idx])Emit module children

concat(a, b, c)Concatenate lists/strings

lookup(key, table)Interpolated table lookup

str(a, b, ...)Build a string

chr(n)Code point → string

ord(s)String → first code point

search(p, s)Substring / list search

version()OpenSCAD version vector

parent_module(idx)Caller stack inspection

Mathematical functions

Trig + scalar + vector math

Trigonometry	Numbers	Lists / vectors
`sin(a)` `cos(a)` `tan(a)`	`abs(x)` `sign(x)`	`len(v)`
`asin(x)` `acos(x)` `atan(x)`	`floor(x)` `round(x)` `ceil(x)`	`norm(v)`
`atan2(y, x)`	`ln(x)` `log(x)` `exp(x)`	`cross(a, b)`
`pow(b, e)` · `sqrt(x)` · `min(...)` · `max(...)` · `rands(min, max, n, seed)`

Trig functions take degrees, not radians.

sin(30) returns 0.5, not -0.988. If you need radians, convert: angle_rad * 180 / PI.

Compact examples

Common shapes

Rounded plate (Minkowski)

minkowski() {
  cube([40, 30, 4]);
  cylinder(r=3, h=0.1);
}

Hollow tube

difference() {
  cylinder(h=40, d=20, $fn=64);
  translate([0,0,-1])
    cylinder(h=42, d=16, $fn=64);
}

Hex grid (list comprehension)

for (x = [0:10:50], y = [0:10:50])
  translate([x, y + (x/10%2?5:0), 0])
    cylinder(h=3, d=8, $fn=6);

Vase via `rotate_extrude`

rotate_extrude($fn=120)
  polygon([
    [0,0], [20,0], [15,20],
    [25,50], [12,60], [0,60]
  ]);

Want any of these as a real STL?

Paste the snippet into the AI CAD Modeler — or describe what you want and the agent will write a parametric version for you, then export it to STL, 3MF, or STEP.

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